Color tint difference between machines, iMac leans on yellow too much

I can see a very noticeable color tint difference between two machines, both running the same version of flux and os x. iMac is a lot more yellow and MacBook Pro is a lot more orange. I'm trying to understand what is going wrong with the iMac and if it's possible to address this without buying a $200 hardware monitor calibrator. Also I think to remember the color tint was more correct in the past so something may have changed along the way but I have no idea what.

I actually just made a huge discovery: when I open the flux preferences and click the "Bedtime" control, it goes super orange like it used to do, like it should :) How come this is not what I'm getting at bed time?

I'm using the same wake time on both machines and the same default settings (recommended colors).

Now I'm not so sure about my previous comment and the "bedtime" control producing different results, I think my eyes were just not used to the quick change. The difference is still noticeable between the two machines so there is still something wrong going on.

That's interesting, thanks! Mine actually seems to turn less warm (more yellow, less orange). I have created a bunch of calibrated profiles via the ColorSync Utility, I will try them out tonight and post the results here.

Quick update: some of the profiles I have created do seem to provide a slightly more orange tone, so nothing radical but still welcome. It is very annoying and difficult to compare as every time I change the profile there is a one-second delay in-between the change where the display goes back to full 'blue' light.